If Amazon founder Jeff Bezos ever wanted to get into the health insurance industry, "the target that would have made sense for them is Cigna," Ana Gupte, senior health care services analyst at Leerink Partners, told CNBC's "Squawk Box."
On Thursday, Cigna agreed to buy Express Scripts in a $54 billion cash-and-stock deal, sending shares of the pharmacy benefit manager more than 15 percent higher on the open.
However, the Cigna offer represents a premium of about double that stock move based on where Express Scripts closed on Wednesday.
There was some speculation that Express Scripts could play a role in the health-care venture being put together by Amazon's Bezos, Berkshire Hathaway's Warren Buffett, and J.P. Morgan's Jamie Dimon. The three corporate titans are aiming to cut health costs for their employees by using their companies' sheer sizes as leverage to get more favorable pricing.
So-called PBMs, such as Express Scripts, negotiate drug benefits for insurance plans and employers.
David Cordani, CEO of Cigna, told "Squawk on the Street" on Thursday he's spoken with "at least two of the three" leaders of the Bezos-Buffett-Dimon venture "in the recent past" about their aspirations.
"Now neither of those entities are now available for Amazon," said Gupte, an analyst with more than 20 years of health care and strategy consulting experience.
The Express Scripts deal may surprise investors given that Cigna had said it was satisfied with its PBM arrangement with UnitedHealth's Optum unit, Gupte later told Reuters.
"It is possible that the threat of an Amazon entry into the healthcare and possibly the drug supply chain landscape, with the latest news of the Amazon-Berkshire Hathaway-J.P. Morgan employer coalition, has spurred Cigna and Express Scripts to tie the knot," she said.
Amazon did not immediately respond to CNBC's request for comment.
The move follows a trend in the health-care industry of companies acquiring assests that do not directly overlap operations. In December, health insurer Aetna announced a $69 billion merger with drugstore chain and PBM CVS Health.
Scott Sperling, co-president of the private equity firm THL Partners, told CNBC said the Cigna-Express Scripts deal makes sense after Cigna's deal with Anthem was blocked by antitrust regulators. "Everyone is looking for ways to reduce the cost of providing health care," he told "Squawk Box." "You're seeing a whole set of these vertical mergers now."
"Express Scripts was under some pressure" by investors to do a deal as well, Sperling added.
Ross Munken, an analyst at researcher Evercore ISI, told CNBC the deal, which will be led by the current Cigna chief Cordani, gives Cigna new capabilities on the PBM side.
The merger ultimately comes down to whether the government believes the deal saves money for the American consumer, he said.
"Obviously, there's not a ton of overlap here in terms of the ... businesses," Munken said. "This is all about if we end up with cheaper drugs as a result" of the deal.